تحقیق تجربی به رفتار سازه از اتصالات عرضی بین بخش های Z فولاد سرد
|کد مقاله||سال انتشار||مقاله انگلیسی||ترجمه فارسی||تعداد کلمات|
|28599||2004||21 صفحه PDF||سفارش دهید||5795 کلمه|
Publisher : Elsevier - Science Direct (الزویر - ساینس دایرکت)
Journal : Thin-Walled Structures, Volume 42, Issue 7, July 2004, Pages 1013–1033
This paper presents an experimental investigation on the structural behaviour of lapped cold-formed steel Z sections. A total of 26 one point load tests on lapped connections between Z sections with various lap lengths and test spans were carried out, and both the strength and the deformation characteristics of these connections were examined in detail. Among all tests, section failure at the end of lap under combined bending and shear was always found to be critical in the connected Z sections. Moreover, the moment resistances of lapped connections with lap lengths equal to 1.2 times section depth were found to develop only 80% of the moment capacities of connected sections. For lapped connections with lap lengths equal to six times section depth, their moment resistances were found to be significantly increased to about 140% of the moment capacities of connected sections. Similar results in the flexural rigidities of the lapped connections were also found. Consequently, it is shown that the degree of structural continuity in lapped connections against bending depend on not only the load levels, the lap length to section depth ratios, but also the lap length to test span ratios. Hence, the widely adopted assumption of full strength and stiffness connections in lapped sections is not always correct. The research work aims to provide understanding to the structural performance of lapped connections between cold-formed steel Z sections, and hence, to develop a set of rational design rules for multi-span purlin systems with overlaps in modern roof construction. The analysis and design method will be fully presented in a complementary paper.
Cold-formed steel sections are lightweight building materials with high strength to self weight ratios, and they are suitable for building construction owing to their versatility in applications, and ease of fabrication and installation. In general, both cold-formed steel C sections and Z sections are widely used in building construction, and the section depths typically range from 100 to 350 mm while the section thicknesses typically range from 1.2 to 3.0 mm. Cold-formed steel sections with yield strengths at 280, 350 and 450 N/mm2 are common while thin cold-formed steel profiled sheetings with high yield strength at 550 N/mm2 are also readily available. In general, design rules on section capacities and member resistances for cold-formed steel sections may be found in various codes of practice , ,  and . However, for connection design, only design rules on the load carrying capacities of individual fasteners are provided while little guidance may be found on the structural behaviour of bolted moment connections.
نتیجه گیری انگلیسی
In order to assess the structural performance of lapped cold-formed steel Z sections, a total of 26 lapped connection tests were executed. In all tests, section failure at the end of lap of connected sections was found to be critical under combined bending and shear. It is demonstrated that both the moment resistances and the flexural rigidities of lapped connections depend not only on the lap length to section depth ratios but also the lap length to test span ratios. Hence, the assumption that lapped sections always have doubled moment resistances and flexural rigidities of those of connected sections is not always correct. Moreover, it is demonstrated that ‘full strength laps’ and ‘full stiffness laps’ may be achieved in lapped connections provided that the lap length to section depth ratios are equal to or larger than 2.0 and 4.0, respectively. Lapped connections with Config. W6 are often stiffer than those with Config. W4 by 3–15% although the differences diminish when the lap lengths increase. The experimental investigation provides not only essential understanding on the structural behaviour of lapped connections but also test data for the calibration of design rules for multi-span purlin systems with overlaps in modern roof construction. The analysis and design is fully presented in a complementary paper.